eyewitness testimonies Flashcards
what is an eyewitness testimony?
the ability of people to remember details of events that they themselves have observed
what are the two factors effecting the accuracy of EWT?
•misleading information
•anxiety
what two forms can misleading information take?
•leading questions: a question that suggests a certain answer
•post event discussion: this could be conversations with witnesses, solicitors or police
what was the method and results of Loftus and Palmers ‘car crash’ study?
•loftus and palmer (1974) arranged for participants (students) to watch film clips of car accidents and gave them questions about it
•in the critical question (a leading question) participants were asked about how fast the cars were travelling
•participants were each asked different questions with different verbs (hit, bumped, collided, smashed)
•different verbs led to different estimated speeds by the participants
•the verb ‘contacted’ resulted in a mean estimate of 31.8mph
•the verb ‘smashed’ was 40.5mph
what is a limitation of loftus and palmers car crash study?
•critics wondered whether the participants were just responding to the ‘forcefulness’ of the verb and questioned whether their memories of the crash were actually changed (whether the car sped up or slowed down in their mind)
what is a strength of loftus and palmers car crash study?
•they conducted a follow- up study
•they conducted a second experiment that supported the substitution explanation, that the word choice in the leading question actually alters the participants memories of the car crash clip
•this is as the participants who heard ‘smashed’ were more likely to report seeing broken glass (even though there was none) by the crash
•did you see the broken glass?
-the ‘smashed’ group were twice as likely to say yes than the ‘hit’ group
•the verb choice does actually alter memories of the incident
what is post-event discussion?
when co-witnesses of a crime discuss it, this may cause (mis)information from others to become incorporated in their own memories
who investigated post-event discussion?
Fiona Gabbert
what was the study conducted into post-event discussion?
•Gabbert and co. studied participants in pairs. each participant watched a video of the same crime, but filmed from different points of view
•both participants then discussed what they had seen before individually completing a test of recall
what were the results of Gabbert’s study?
•the researcher found that 71% of the participants mistakenly recalled aspects of the event that they had not seen but had picked up in the discussion
•the corresponding figure in a control group (ones that didn’t discuss what they had seen) was 0%
•Gabbert concluded that witnesses often go along with eachother, either to win social approval or because they believe other witnesses are right and they are wrong
what is it called when people change their eyewitness testimonies due to post-event discussion?
memory conformity
what is a strength of the post-event discussion study?
•research has led to changes in the criminal justice system
•courts are much more cautious when presented with EWT as evidence
what is are 3 limitations of post-event discussion studies?
•research into EWT has involved very artificial activities being conducted in laboratories and is criticised for lacking ecological validity. This means the same results may not be found in real-life situations
•in real life, being a witness to a crime can make a significant emotional impact on the individual. However, the memory recall tasks performed in lab based studies does not have this emotional significance
•participants in research studies are usually ready to be cooperative, and therefore are even more likely to be influenced by leading questions. This ‘acquiescence bias’ weakens the validity of the research findings.
what effect does anxiety have on recall?
anxiety can have a positive or negative effect on recall
who conducted a study saying anxiety has a negative effect on recall?
Johnson and Scott
What was the method of johnson and scott’s study?
•they made participants think they were going to take part in a lab study, and while seated in a waiting area they head an argument in the next room
•in the ‘low anxiety’ condition, a man walked through the waiting area carrying a pen with grease on his hands
•in the ‘high anxiety’ condition, participants overheard the same argument but then accompanied by the sound of breaking glass. then a man walked out with a paper knife that was covered in blood
Results of Johnson and Scott’s study
Later, participants had to pick out the man from a set of 50 photos
•in the ‘low anxiety’ group (with the pen), 49% of people successfully identified the man
•in the ‘high anxiety’ group (with the knife), 33% of people successfully identified the man
what is the tunnel theory of memory?
the tunnel theory of memory argues witness attention narrows to focus on a weapon, because it is a source of anxiety
who conducted a study saying anxiety has a negative effect on recall?
Valentine and Mesout
method of valentine and mesout’s study
•they carried out a study in a real life setting of the Horror Labyrinth at the London Dungeon
•there were two conditions, high anxiety and low anxiety
•the participants heart rates were detected to measure the levels of stress as they went through the experience
•afterwards, the participants were asked to describe details of an actor in the labyrinth
results of Valentine and mesout’s study
•17% of the high anxiety group correctly identified the actor in a line up
•75% in the low anxiety correctly identified the actor
what percentage of the low anxiety group in johnson and scott’s study identified the man
49%
what percentage of the high anxiety group in johnson and scott’s study successfully identified the man?
33%
who investigated the notion that anxiety had a positive effect on recall?
Yuille and Cutshall
what was the method of Yuille and Cutshall’s research?
•they conducted a study of a real life shooting in vancouver
•there were 21 witnesses, 13 agreed to take part in the study
•participants were asked to rate how stressed they were when they witnessed the event
•interviews were held just after the event, and 4-5 months later
•participants who had rated themselves as more stressed often had better recall, and the accuracy didn’t change much between the initial interviews and 5 months later
what were the results of Yuille and Cutshall’s study
•88% of accuracy after 5 months in the high stress group
•75% for the less stressed group
who came up with the term flashbulb memories?
Brown and Kulik
what are flashbulb memories?
•these are a vivid imprint of events surrounding an important incident. the events tend to have a high level of emotional arousal
•it is thought that they adrenalin released in highly stressful situations lead to the forming of an enduring image or memory
•this concept supports the argument that arousal has a positive impact on memory recall
two limitations of the effect of anxiety on EWT
•contradictory research
•weapon focus may not be relevant
evaluating the effect of anxiety on EWT
limitation: contradictory research
•some research studies suggest that anxiety has a positive impact on recall, whereas others suggest it has a negative impact on recall
•this is explained using the Yerkes-Dodson law (the inverted U curve)
•the curve suggested that increased anxiety and physical arousal would improve memory functioning up to a point, beyond which functioning would deteriorate
evaluating the effect of anxiety on EWT
limitation: weapon focus effect may not be relevant
•weapon focus research may test surprise rather than anxiety. the reason the participants focus on the weapon may be due to surprise
•as suggested my Pickel’s study, concluding that weapon focus is due to unusualness and rather than anxiety so therefore tells us nothing specifically about the effects of anxiety on EWT
Pickel’s study
•he conducted an experiment using scissors, a handgun, a wallet, or a raw chicken to rob a hairdressing salon
•eyewitness accuracy was significantly poorer in the more unusual conditions (chicken leg or handgun)
•this suggests that the weapon focus effect is due to unusualness rather than anxiety/ threat and therefore tells us nothing specifically about the effects of anxiety on EWT
who introduced the cognitive interview?
Gieselman
what is the cognitive interview?
it is thought to be superior to a standard interview, where there is simply a free recall of events
the 4 stages of the cognitive interview
stage 1: report everything
stage 2: re-instate the context
stage 3: reverse the order of recall
stage 4: change perspective
what does ‘re-instate the context’ mean?
•the witness is asked to mentally return to the scene and re experience the internal/ psychological conditions and external, environmental factors
why are stages 1 and 2 of the cognitive interview useful?
they are techniques based upon the encoding specificity principle. memories become ‘linked’ at the time of encoding, so both state (internal) and context (external) cures can trigger recall of other connected information
why are stages 3 and 4 of the cognitive interview useful?
they are both techniques to counteract the influence of schemes on how events are recalled. schemas are mental frameworks of knowledge we have acquired to make sense of the world
how do schemas influence our memory?
if our recall is uncertain, these schemes provide us with assumptions about what may have occurred- but these can be incorrect. so if the witness ‘changes the order’ or perspective they are prevented from relying on their schemas
in Gabbert’s study, what percentage of participants mistakenly recalled information due to post-event discussion?
71%
